I gotta admit, where does this definition of "sapient" come from? Sapient seems to have arisen in recent years as something different from sentient, but, I have no idea what that difference is.
Humans are sentient. A dog is sapient - it is capable of perceiving the world around it. But, I wouldn't call a dog sentient.
"Sapience" is a somewhat more recent term in public usage (though quite old in scientific usage), which cropped up as a result of the casual, everyday use of the word "sentient" being at odds with its scientific definition.
Conflicts like this arise quite often in the contrast between scientific jargon (which is usually very precise) and common usage (which often latches onto whatever first happened and runs with it). "Bisexual," for example,
originally meant "someone who has two anatomical sexes," e.g., what we now call "hermaphroditic" today. Kinsey, the well-known biologist and sexologist, particularly disliked the use of the term "bisexual" to refer to people who were attracted to both male and female partners, but he just flatly lost that battle in the long run. Now, "bisexual" is almost universally used as an orientation term, not an anatomy term.
The reverse situation happened with "sentient" vs "sapient." "Sentient" refers to the ability to feel sensations and (generally) emotions of some kind, however limited; it comes from the Latin
sentiens, "feeling," present participle of
sentio, "I feel." Often, the ability to experience pain is one of the most relevant standards for sentience, as that means not just experiencing injury, but the additional harm of
suffering. So, for example, ants would generally not be considered sentient, but all vertebrates (fish, frogs, birds, mammals, etc.) are. Cnidarians, aka jellyfish, are another example of a clade where there
is a nervous system present, but it's delocalized, and thus jellyfish are not generally believed to be sentient by most zoologists and neurologists today.
(As an aside,
some of the blame here can be placed on Descartes, who thought all non-human animals were pure automata, completely incapable of sentient experience to even the smallest degree. The scientific consensus of the 20th century is that this is absolute bunk.)
As a result, a different term is needed for the dramatic level of cognitive difference between humans and most or possibly all other extant life on our planet, and one already exists: "sapient." It comes from the Latin
sapiens, which you've heard about from our species name,
Homo sapiens, meaning "wise man." (Ultimately,
sapiens is the present participle of
sapio, which means both "I am wise"/"I know [how to do]" and "I taste," presumably arising from a meaning centered on how taste requires discernment and judgment.) Hence, a sapient being is not merely sentient, though that is certainly a requirement for sapience, but rather capable of all the emotions and cognitive states a human is capable of.
The shift from "sentient" to "sapient" in literature and the public media is a product of, as far as I can tell, about the last 25-30 years or so. Prior to that, science fiction was perfectly comfortable using "sentient" exclusively. I suspect the shift is mostly due to a rise in scientific study of neurobiology, public awareness of the technical terms involved, and a desire for "harder" science fiction, that takes real scientific concepts and jargon seriously.